Flanged connections have a wide variety of industrial uses including connecting structural members that will be subjected to critical external loads and in sealing high pressure vessels. The flanges used in such applications must be maintained in face-to-face contact to ensure proper operation. This face-to-face contact is maintained by the plurality of fasteners that are tightened to a high percentage of their yield strength. It is well known in the art that such flanges bend in an axial or meridional direction during this tightening procedure. This meridional bending is transmitted to the fasteners, contributes significantly to the stress in the fasteners, and reduces the amount of tightening to which the fasteners can be safely subjected. As a consequence, the bending reduces the face-to-face contact between the flanges and therefore also the load to which the flanged connections can be subjected.
Flanged connections play a particularly significant role in the oil and gas industry where large diameter tubular members with flanged end connections, called “risers” or “riser joints,” are used. These risers are used in offshore drilling and production operations and extend from the wellhead at the ocean floor to a surface vessel. A drawback of conventional flanged connections that is specific to risers is that flanged connections often dictate the manner in which risers are connected, commonly referred to as either “pin up” or “box up.” Conventional flanges are designed to either be a bottom flange or a top flange, and are designed to either connect risers in a pin up or a box up configuration, but not both. As a consequence, this lack of robustness from conventional flanged connections hinders riser connection innovation. Because flanged connections between adjacent riser joints must contain internal pressure along with enormous external loads due to environmental conditions, it is critical that these flanged connections, and the fasteners holding them together, function flawlessly and enable innovative riser connection designs.